"658 days into his administration, President Obama has shown no sign that he is aware that the Constitution gives the president clemency powers," political science professor P.S. Ruckman Jr. wrote on his blog, "Pardon Power," Tuesday. That's a sorry comment to throw at a former constitutional law professor who, in less than two weeks, "will pass Bill Clinton and become the slowest Democratic president in history to exercise the pardon power."

For Clarence Aaron, Barack Obama's failure to act must seem unspeakably cold. In 1993, Aaron was sentenced to life without parole for a first-time nonviolent federal drug offense. Now, he deserved to go to prison -- but his life-until-death sentence demonstrates that a system designed to be tough on drug kingpins has been subverted so that big-time dealers can do short time for testifying against their underlings.

The story starts in 1992, when a financially strapped Aaron made some bad -- criminal -- decisions. A childhood friend who worked for a major Alabama drug dealer was looking for connections in Baton Rouge, La., where Aaron attended Southern University. Aaron introduced the friend to a classmate's brother. The kingpin gave Aaron's friend $200,000 to buy about 20 pounds of cocaine. Aaron was there. Another deal, which didn't happen, would have moved an additional 33 pounds of cocaine. For his role, Aaron received $1,500.

Now Aaron is in prison for the rest of his life, while all but one of the career dealers have served their time and been set free.

Kingpin Marion Teano Watts testified that he had made more than $1 million selling crack in Mobile, Ala. He faced a sentence of life without parole. Watts testified against Aaron, was sentenced to 14 years and served less than eight. Aaron's childhood friend served four years. Only the Baton Rouge dealer, who faced other cocaine charges, remains in prison -- and he is due for release in 2014.

Aaron's biggest crime, it turns out, was not conspiracy to distribute cocaine. He could have been a big dealer, snitched on the career criminals and been free by now. But because he was a college kid unfamiliar with the courts, Clarence Aaron did not know how to game the system.

Now he's a 41-year-old inmate who has paid his debt to society and taken responsibility for his misdeeds. Aaron has had a good record in prison. He has supporters who say they will hire him if he is released.

Yes, presidential pardons carry political risk. Former GOP Arkansas Gov. Mike Huckabee commuted the sentence of a violent felon with a history of prison violations, including fighting. Maurice Clemmons later killed four Washington police officers.

Obama can avoid those pitfalls by focusing on nonviolent drug offenders serving outrageously long time behind bars because of the Draconian federal mandatory minimum sentencing system. He can limit clemency to inmates with clean prison records. He can commute prison terms but require that inmates be released under supervision.

I can't prove that as an African-American man, Clarence Aaron was subjected to a harsher sentence than would have been imposed on a white college student. But as Aaron told me over the phone in 2002, "I don't see too many young white kids coming into the penitentiary."

In "The Audacity of Hope," Obama wrote that he hoped he could remain honest as a U.S. senator. As president, he cannot honestly believe that a 23-year-old first-time nonviolent drug offender should be sentenced to life without parole.